Connector plates are typically used to connect wood members to form trusses and joists. Connector plates are produced by feeding a steel plate into a stamping press. In the press, the steel plate is punched between a plurality of blade punches and a corresponding number of die cavities in a receiver or die block. In use, a connector plate has a planar steel backing with a plurality of teeth extending generally perpendicular to the backing.
Manufacturers of connector plates are constantly seeking ways to increase the strength characteristics of the connector plate teeth and to improve the methods of manufacture. The shape and strength characteristics of the teeth depend largely on the configuration of the blade punch and the die used to produce the teeth.
Problems are often encountered in the production of connector plate teeth. One such problem occurs as a formed connector plate is stripped from the die block. Often the connector plate teeth will bind in the die cavity. Another such problem is the fracturing of connector plate teeth at their roots as they are bent over the ends of the die cavity. Further, some currently used punch and die sets produce unwanted "viper teeth," or teeth with tears or rips along the side edges. This is especially a problem when higher grade steels are used to produce the connector plates. Unwanted fractures and tears reduce the strength of connector plate teeth and detrimentally affect the performance of the plate.
It is an object of the present invention to provide a punch and die set that consistently produce connector plate teeth of desired shape and strength and avoid the manufacturing problems encountered in many punch and die operations.